1. Field of the Invention
The present invention relates to an constant abrasive feeder of abrasive grains, which is used for a high precision micro machine device for shot blasting or shot peening and capable of stably supplying a constant quantity of abrasive grains to an abrasive jet nozzle. More particularly, the invention relates to the constant abrasive feeder of abrasive grains suitable for shot blasting, i.e., fine shot blasting which is conducted while stably supplying a constant quantity of fine materials.
2. Description of Related Art
A conventional shot blasting has been utilized as relatively rough finishing means, for example, for deburring or descaling from castings using the abrasive grains having size of several hundreds xcexcm or greater with high fluidity. Therefore, the shot blasting could be carried out without providing the constant abrasive feeder of abrasive grains separately (see Utility Model Application Laid-Open sho 47-26491).
The working processes such as blasting finishings (machinings) have been wanted to apply to fine finishings, because the blasting finishings are carried out without chemicals which pollute the water. The applications are exemplified: formations of barrier ribs on a plasma display panel (PDP) and of electrodes on a dielectric filter, the formations have been conventionally carried out with chemical etchings or screen printings.
However, such fine work utilizes the abrasive grains having a size of several tens xcexcm or smaller. If the size of the abrasive grains becomes several tens xcexcm or smaller, a constant quantity of abrasive grains can not be stably supplied to the abrasive jet nozzle due to pressure of the fluid such as air utilized for blasting the abrasive grains from the abrasive jet nozzle.
According to the conventional apparatus disclosed in Japanese Patent No. 2876400, a reservoir tank and a buffer tank are arranged to constitute a reservoir supply section, which supplies a constant quantity of the reserved abrasive grains so as to be intermittently supplied to a vibration feeder air-tightly. As a result, a constant quantity of the abrasive grains can be supplied to the abrasive jet nozzle in a stable manner.
However, in the conventional apparatus disclosed in Japanese Patent No. 2876400, when supplying a constant quantity of abrasive grains from the reservoir supply section to the vibration feeder, it is intensively supplied from the buffer tank disposed in the reservoir supply section while pouring the abrasive grains into a funnel in the vibration feeder. As a result, the abrasive grains coagulates in the buffer, thus causing bridging state. Therefore, it has been difficult to stably supply the constant quantity of the abrasive grains to the abrasive jet nozzle.
In view of the foregoing problems, it is an object of the present invention to provide an constant abrasive feeder of abrasive grains, which uses fine abrasive grains circularly and allows stable supply of the recovered abrasive grains to the abrasive jet nozzle by preventing the material from being bridged.
In the constant abrasive feeder of the abrasive grains,
the abrasive grains blasted from an abrasive jet nozzle is recovered in a cyclone which separates the abrasive grains from the dust mixed in the abrasive grains, and the abrasive grains is supplied to be reserved in a reservoir supply section to supply a constant quantity of the reserved abrasive grains sequentially to the abrasive jet nozzle by a vibration feeder;
the reservoir supply section disconnects a communication state to the vibration feeder at the inflow of the recovered abrasive grains, and disconnects a communication state to the cyclone at the supply of the abrasive grains to the vibration feeder;
the vibration feeder includes a feeder body and a vibrator such that the constant quality of the abrasive grains supplied from the reservoir supply section is transferred on a feeder and supplied to the abrasive jet nozzle; and
a stirring hopper is disposed between the reservoir supply section and the vibration feeder for stirring the constant quantity of the abrasive grains sent from the reservoir supply section so as to be supplied to the vibration feeder.
Therefore, the abrasive grains blasted from the abrasive jet nozzle is recovered in a cyclone where it is separated from the dust attached thereto. Then the dust is collected by the dust collector such that only the abrasive grains can be fed to the reservoir supply section. At this time, the reservoir supply section reserves a constant quantity of the abrasive grains fed from the cyclone so as to be sent to a stirring hopper.
At this time, the reservoir supply section reserves a constant quantity of the abrasive grains fed from the cyclone and disconnect the communication state with the cyclone so as to prevent pressure fluctuation by bringing the reservoir supply section, stirring hopper portion and the vibration feeder into an air-tight state.
The stirring hopper stirs the constant quantity of the abrasive grains supplied from the reservoir supply section to fractionate the abrasive grains which is likely to clump together such that it can be fed to the vibration feeder. This makes it possible to prevent the flow of the reserved abrasive grains from being suspended in the stirring hopper.
Thereafter, the constant quantity of abrasive grains is supplied to the abrasive jet nozzle from the vibration feeder so as to be blasted to the work through the abrasive jet nozzle. Therefore, this apparatus can stably supply the constant quantity of abrasive grains to the vibration feeder with no pressure fluctuation through stirring in the stirring hopper to prevent suspension of the material flow.
As described above, the apparatus of the present invention can stably supply the constant quantity of abrasive grains to the abrasive jet nozzle using the fractionated abrasive grains in a circulating manner.
A constant quantity of fractionated low fluidity abrasive grains with a size of several tens xcexcm or smaller can stably be supplied. Accordingly the present invention may be applied to high precise micro machine device so as to enhance the precision of machining as well as the yield resulting from reduced number of defect parts.
Further, the reservoir supply section includes a reservoir tank and a buffer tank vertically aligned in a two-stage manner. At the inflow of the recovered abrasive grains, an opening/closing shutter disposed in the buffer tank is closed to disconnect the communication state to the vibration feeder. At the supply of the abrasive grains to the vibration feeder, an opening/closing shutter disposed in the reservoir tank is closed to disconnect the communication state to the cyclone.
Therefore, at the supply of the abrasive grains from the reservoir supply section to the stirring hopper, if the communication to the cyclone is disconnected, i.e., if the opening/closing shutter of the reservoir located in the upper stage is closed at the supply of the abrasive grains to the stirring hopper, the material reserved in the buffer tank located in the lower stage can be supplied with no pressure fluctuation in the state where the reservoir supply section, stirring hopper and vibration feeder are kept air-tight.
Further, the stirring hopper is formed of a hopper including a cylindrical stirring hopper and a reservoir tank with its shape tapered downward, a supply guide disposed downward of the hopper, and a hopper connected to a power source and capable of stirring the abrasive grains.
Therefore, in the stirring hopper, the stirring section connected to the power source stirs the constant quantity of abrasive grains supplied from the reservoir supply section and reserved in the reservoir shaped tapered downward for the supply to the supply guide. Therefore, the reserved abrasive grains which is likely to clump together can reliably be fractionated so as to prevent the flow of the reserved abrasive grains from being suspended.
Further, the vibrator vibrates the abrasive grains supplied from above such that the vibration feeder supplies the abrasive grains to an outlet port formed in the lower portion.
Therefore, the vibration feeder receives the abrasive grains stirred and fractionated in the stirring hopper and supplies it from the upper stirring hopper to the lower outlet port through vibration of the vibrator. This makes it possible to prevent clump of the abrasive grains during transfer such that a constant quantity of the material can be reliably supplied to the abrasive jet nozzle in a stable manner.